Sensitivity to light, or photophobia, occurs when there are abnormalities in the tear film and ocular surface. Normally, the tear film protects nerve endings from the irritation of light. The cornea and tears combine to create a smooth, lubricated surface that is an important component in focusing light. When tear film is inadequate or unstable, it is not as effective in focusing light properly. The result can be pain or sensitivity to light.
Some people only feel discomfort from bright lights, while others cannot stand any type of light, whether it is sunlight, fluorescent light, incandescent light, or candle flames. Some light-sensitive people tend to squint or close their eyes when exposed to light.
There are many different causes of photophobia, but it is usually a symptom of another condition or disease.
Photophobia happens to people of all ages and both sexes. It can be temporary or constant. A common temporary occurrence happens after leaving a movie theatre. To eyes that have adjusted to the dim lights inside the theater, bright lights outside the theater can be almost unbearable. This type of increased sensitivity to light is temporary. Constant photophobia, on the other hand, is usually an indicator of another problem, including Dry Eye, for which medical attention should be sought.
From: EyeNet Magazine